1. Field of the Invention
The present invention relates to an ink jet recording device and a short circuit protection method for an ink jet recording device.
2. Description of the Related Art
Ink jet recording devices are being used in various applications as image forming devices such as copiers, printers, and fax machines. In an ink jet recording device, a recording operation is performed by discharging minute ink droplets onto a recording medium from an ink jet recording head corresponding to each color ink. In the discharge operation of ink droplets, a drive signal is inputted to a drive element such as a piezoelectric element provided in an ink flow path communicated with a discharge port so as to cause a pressure fluctuation in the ink inside the ink flow path and thereby cause the ink to be discharged from the discharge port, for example.
When a high-definition color image is formed, an ink jet recording head having a large number of densely-arranged discharge ports is used. In such an ink jet recording head, a large number of drive elements are densely arranged so as to correspond to the respective discharge ports. Head drive circuits are densely provided to the respective drive elements via wiring.
When an electric short circuit is generated in the head drive circuit, an overcurrent is applied thereto, thereby damaging the circuit or a component thereof. Thus, the head drive circuit is provided with a protection circuit for preventing such a trouble.
For example, Japanese Laid-open Patent Publication No. 10-128965 (1998-128965) describes an ink jet printer that detects impedances of a data line and an address line associated with a nozzle and interrupts the data line or the address line in order to prevent the damage of a driver circuit in the thermal ink jet printer.
Japanese Laid-open Patent Publication No. 2010-76312 describes a liquid discharge head drive circuit that monitors a current applied to a common line and restricts a common current when the common current which increases along with a reduction in an insulation resistance of a piezoelectric element exceeds a reference value in order to protect the liquid discharge head drive circuit, etc.
The ink jet printer described in Japanese Laid-open Patent Publication No. 10-128965 (1998-28965) and the liquid discharge had drive circuit, etc. described in Japanese Laid-open Patent Publication No 2010-76312 are each provided with a circuit for protecting the head drive circuit of the ink jet recording e. However, there is a risk that the waveform of a drive signal may be changed due to the application of a drive current to the protection circuit and this is undesirable in performing the drive control of the drive element. Moreover, regarding a circuit component used in the protection circuit, there is a problem such as increasing in size and cost of the protection circuit as a result of the use of a large-size component and an expensive component.
In view of such problems in conventional techniques, there is a need to configure a current interruption element for protecting a current amplifier circuit from a short circuit of a drive signal by employing a small and inexpensive circuit component in an ink jet recording device.